The aim of this project is to further the understanding of the developmental mechanisms which cause regional cellular differentiation in the ductal components of salivary glands. A murine submandibular sialomucin has been electrophoretically purified to homogeneity and characterized biochemically. Antisera prepared against it has indicated by immunofluorescence studies that within the submandibular gland, the mucin is an unambiguous indicator of acinar cell specialization. The antisera has been shown to perform in a radioimmunoassay and this reaction is currently being evaluated for its sensitivity and specificity. The goal is to be able to quantitate the mucin within the submandibular gland and in the saliva. We have previously shown that parotid cells continue to produce alpha-amylase for several weeks in culture. The antiserum against the acinar cell mucin will be used as part of a study with cultured submandibular cells to determine if the acinar cells proliferate in culture. Other projects are underway to prepare and to characterize the mucin protein core and also to measure the rates of mucin synthesis.